Bone Toolbox: Biomarkers, Imaging Tools, Biomechanics, and Histomorphometry

Chronic di(2-ethylhexyl) phthalate exposure at environmental-relevant doses induces osteoporosis by disturbing the differentiation of bone marrow mesenchymal stem cells

Di(2-ethylhexyl) phthalate (DEHP) is a widely used plastic additive with persistent characteristics in the environment. This study was designed to investigate the detrimental effects of chronic DEHP exposure at environmental-relevant doses on bone metabolism and the underlying mechanisms. It was found that exposure to 25 μg/kg bw and 50 μg/kg bw DEHP for 29 weeks led to a reduction of whole-body bone mineral density (BMD), femur microstructure damage, decreased femur new bone formation, and increased femur bone marrow adipogenesis in C57BL/6 female mice, which was not observed in mice exposed to 5000 μg/kg bw DEHP. Further in vitro study showed that DEHP treatment robustly promoted adipogenic differentiation and suppressed osteogenic differentiation of the bone marrow mesenchymal stem cells (BMSCs). Mechanistically, DEHP exposure resulted in elevated expressions of DYRK1B, CDK5, PPARγ, and p-PPARγSer273 in both bone tissue and BMSCs. Interestingly, co-IP analysis showed potential interactions among DYRK1B, PPARγ, and CDK5. Lastly, antagonists of DYRK1B and CDK5 effectively alleviated the BMSCs differentiation disturbance induced by DEHP. These results suggest that DEHP may disturb the BMSCs differentiation by upregulating the PPARγ signaling which may be associated with the activation of DYRK1B and CDK5.

Biomechanical and histomorphological analysis of the mandible in rats with chronic kidney disease

The present study aimed to investigate the biomechanical and histomorphological features of mandibles in an adenine-induced chronic kidney disease-mineral and bone disorder (CKD-MBD) rat model of CKD. A total of 14 Sprague-Dawley rats were randomized into the following two groups: control group and CKD group. At the end of the sixth week, all rats were euthanized, and serum was collected for biochemical marker tests. Macroscopic bone growth and biomechanical parameters were measured in the right hemimandible, while the left hemimandible was used for bone histomorphometric analysis. Compared to the control group, the CKD group showed a significant increase in serum creatinine, blood urea nitrogen, and serum parathyroid hormone at the end of the sixth week. The biomechanical structural properties significantly decreased in the CKD group compared to the control group. Bone histomorphometric analysis indicated that the trabecular bone volume of rats in the CKD group was significantly lower than that of the control group. In the CKD groups, the bone formation parameters of the trabecular bone were significantly increased, while the bone mineralization apposition rates of both the trabecular bone and periosteal cortical bone were significantly increased. The rat CKD model showed deteriorated structural mechanics, low trabecular bone volume, high trabecular bone formation, increased trabecular bone mineralization apposition rate, and increased cortical bone mineralization apposition rate, which met the characteristics of osteitis fibrosa, indicating that this model is a useful tool for the study of mandible diseases in CKD patients.

Diabetic microvascular disease in non-classical beds: the hidden impact beyond the retina, the kidney, and the peripheral nerves

Diabetes microangiopathy, a hallmark complication of diabetes, is characterised by structural and functional abnormalities within the intricate network of microvessels beyond well-known and documented target organs, i.e., the retina, kidney, and peripheral nerves. Indeed, an intact microvascular bed is crucial for preserving each organ's specific functions and achieving physiological balance to meet their respective metabolic demands. Therefore, diabetes-related microvascular dysfunction leads to widespread multiorgan consequences in still-overlooked non-traditional target organs such as the brain, the lung, the bone tissue, the skin, the arterial wall, the heart, or the musculoskeletal system. All these organs are vulnerable to the physiopathological mechanisms that cause microvascular damage in diabetes (i.e., hyperglycaemia-induced oxidative stress, inflammation, and endothelial dysfunction) and collectively contribute to abnormalities in the microvessels' structure and function, compromising blood flow and tissue perfusion. However, the microcirculatory networks differ between organs due to variations in haemodynamic, vascular architecture, and affected cells, resulting in a spectrum of clinical presentations. The aim of this review is to focus on the multifaceted nature of microvascular impairment in diabetes through available evidence of specific consequences in often overlooked organs. A better understanding of diabetes microangiopathy in non-target organs provides a broader perspective on the systemic nature of the disease, underscoring the importance of recognising the comprehensive range of complications beyond the classic target sites.

Non-traditional HIIT-style ROTC training elicits positive bone quality and performance adaptations

Military personnel experience elevated bone injury incidence, partly due to arduous and repetitive training. Non-traditional High-Intensity Interval Training-style (HIIT) may benefit pre-enlisted Reserve Officer Training Corps (ROTC) cadet's musculoskeletal health and performance prior to military service. This study investigated 16 ROTC (n = 12 males; n = 4 females) and 15 physically active sex-, age-, and body mass-matched Controls' musculoskeletal health and performance from November to April. Total body, lumbar spine, and dual- hip dual-energy X-ray absorptiometry scans and 4%, 38%, 66% tibial peripheral quantitative computed tomography scans, blood draws (serum sclerostin and parathyroid hormone), and maximal muscle strength and aerobic capacity testing were completed. From November to April, ROTC improved bone density (DXA) of the dominant total hip and greater trochanter and non-dominant greater trochanter and 38% and 66% tibial total volumetric and cortical bone density (pQCT) similarly or more than Controls (all p ≤ 0.049). From November to April, ROTC also improved bench and leg press, and peak aerobic capacity (all p ≤ 0.013). From November to January, serum sclerostin increased (p ≤ 0.007) and remained elevated through April, while parathyroid hormone was unchanged. HIIT-style training induced positive musculoskeletal adaptations, suggesting it may be an excellent pre-service training modality for this injury prone group.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Juvenile Bone Toxicity: Study Considerations, Regulations, and Techniques for Assessment

Recommendations on study designs that adequately evaluate the in-life effects leading to juvenile bone toxicity, the various imaging modalities that can aid interpretation of the bone effects, biomarkers that may be useful, and regulatory issues were presented in this 2020 ACT symposium. The pathologies encountered in past studies were briefly mentioned. The first speaker covered study design and the numbers of juveniles that may be necessary to power the evaluation. Changes in the International Council for Harmonisation (IHC) guidelines were reviewed. The second speaker launched the rest of the symposium by describing the tools that may help assess juvenile bone toxicity, specifically those used to monitor bone toxicity, healing, and remodeling as they relate or drive the study design including model, species selection, and age. The third speaker addressed in more depth the micro-Computed Tomography (CT) applications in juvenile toxicology for evaluation of skeletal elements and bone growth in both embryo-fetal development (EFD) and pre and postnatal development (PPND) studies. Lastly, a regulatory perspective on strategies to assess juvenile bone toxicity and the concerns of the regulatory agency with respect to these potential changes in the juvenile population was addressed.

Associations Between Inflammatory Mediators and Bone Outcomes in Postmenopausal Women: A Cross-Sectional Analysis of Baseline Data from the Prune Study

Purpose

Hypoestrogenism triggers increased production of inflammatory mediators, which contribute to bone loss during postmenopausal osteoporosis. This study aimed to investigate the association between circulating inflammatory markers and bone outcomes in postmenopausal women.

Materials and methods

We conducted a cross-sectional, secondary analysis of baseline data from participants who completed a 12-month randomized controlled trial, The Prune Study (NCT02822378), which included healthy postmenopausal women (n=183, 55-75 years old) with bone mineral density (BMD) T-score between 0.0 and -3.0 at any site. BMD was measured using dual-energy X-ray absorptiometry, and bone geometry and strength were measured using peripheral quantitative computed tomography. Blood was collected at baseline to measure (1) serum biomarkers of bone turnover, including procollagen type 1 N-terminal propeptide (P1NP) and C-terminal telopeptide and (2) inflammatory markers, including serum high-sensitivity C-reactive protein (hs-CRP) and plasma pro-inflammatory cytokines, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, and monocyte chemoattractant protein (MCP)-1, using enzyme-linked immunosorbent assay. The associations between bone and inflammatory outcomes at baseline were analyzed using correlation and regression analyses.

Results

Serum hs-CRP negatively correlated with P1NP (r=-0.197, p=0.042). Plasma IL-1β, IL-6, IL-8, and TNF-α negatively correlated with trabecular bone score at the lumbar spine (all p<0.05). In normal-weight women, plasma IL-1β, IL-6, and IL-8 negatively correlated (p<0.05) with trabecular and cortical bone area, content, and density at various sites in the tibia and radius. Serum hs-CRP positively predicted lumbar spine BMD (β=0.078, p=0.028). Plasma IL-6 negatively predicted BMD at the total body (β=-0.131, p=0.027) and lumbar spine (β=-0.151, p=0.036), whereas plasma TNF-α negatively predicted total hip BMD (β=-0.114, p=0.028).

Conclusion

At baseline, inflammatory markers were inversely associated with various estimates of bone density, geometry, and strength in postmenopausal women. These findings suggest that inflammatory markers may be an important mediator for postmenopausal bone loss.

Calcium status assessment at the population level: Candidate approaches and challenges

Inadequate dietary calcium intake is a global public health problem that disproportionately affects low- and middle-income countries. However, the calcium status of a population is challenging to measure, and there are no standard methods to identify high-risk communities even in settings with an elevated prevalence of a disease caused or exacerbated by low calcium intake (e.g., rickets). The calcium status of a population depends on numerous factors, including intake of calcium-rich foods; the bioavailability of the types of calcium consumed in foods and supplements; and population characteristics, including age, sex, vitamin D status, and genetic attributes that influence calcium retention and absorption. The aim of this narrative review was to assess candidate indicators of population-level calcium status based on a range of biomarkers and measurement methods, including dietary assessment, calcium balance studies, hormonal factors related to calcium, and health outcomes associated with low calcium status. Several promising approaches were identified, but there was insufficient evidence of the suitability of any single indicator to assess population calcium status. Further research is required to develop and validate specific indicators of calcium status that could be derived from the analysis of data or samples that are feasibly collected in population-based surveys.

Current Status of the Diagnosis and Management of Osteoporosis

Osteoporosis has been defined as the silent disease of the 21st century, becoming a public health risk due to its severity, chronicity and progression and affecting mainly postmenopausal women and older adults. Osteoporosis is characterized by an imbalance between bone resorption and bone production. It is diagnosed through different methods such as bone densitometry and dual X-rays. The treatment of this pathology focuses on different aspects. On the one hand, pharmacological treatments are characterized by the use of anti-resorptive drugs, as well as emerging regenerative medicine treatments such as cell therapies and the use of bioactive hydrogels. On the other hand, non-pharmacological treatments are associated with lifestyle habits that should be incorporated, such as physical activity, diet and the cessation of harmful habits such as a high consumption of alcohol or smoking. This review seeks to provide an overview of the theoretical basis in relation to bone biology, the existing methods for diagnosis and the treatments of osteoporosis, including the development of new strategies.

Examining effects of habitual physical activity and body composition on bone structure in early post-menopausal women: a pQCT analysis

After menopause, bones decline in structure and can break more easily. Physical activity can strengthen bones. This study investigated how activity and body composition can impact bone structure in post-menopausal women. Higher levels of physical activity were positively associated with bone structure at the lower leg.

PURPOSE

The menopausal transition is characterized by dramatic bone loss, leading to an increased risk of fracture. Few studies have examined how modifiable risk factors influence bone structure. Thus, the objective of this cross-sectional study was to examine the relationship between habitual physical activity (PA), body composition, and bone structure in post-menopausal women with low bone mass.

METHODS

Data was analyzed from 276 post-menopausal women with low bone mass enrolled in the Heartland Osteoporosis Prevention Study. Body composition and bone structure measures were collected using dual X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) at the tibia. Habitual PA was collected using the Human Activity Profile questionnaire. Multiple regression analysis was used to determine the relative impact of habitual PA and body composition on bone structure measures (density, area, and strength). Direct and/or indirect effects of PA on bone outcomes were assessed by path analysis.

RESULTS

Mean (± SD) age of participants was 54.5 (± 3.2) years and average BMI was 25.7 (± 4.7). Mean T-score of the total lumber spine and hip were - 1.5 (± .6) and - 0.8 (± .59), respectively, with all women classified with low bone mass. Habitual PA had a significant positive effect on bone area and strength measures at the 66% site, and trend effects at the 4% site. Lean mass had a significant positive effect on area and strength at the 66% site and 4% site. Fat mass showed no effect at the 66% site, with a positive effect on density and strength at the 4% site.

CONCLUSION

Increased habitual activity was related to improved bone structure of the tibia. Our results in post-menopausal women emphasize that PA and lean mass preservation are important for maintaining bone structure in the years following menopause.

Mechanical stimuli-mediated modulation of bone cell function-implications for bone remodeling and angiogenesis

Bone remodeling, expressed as bone formation and turnover, is a complex and dynamic process closely related to its form and function. Different events, such as development, aging, and function, play a critical role in bone remodeling and metabolism. The ability of the bone to adapt to new loads and forces has been well known and has proven useful in orthopedics and insightful for research in bone and cell biology. Mechanical stimulation is one of the most important drivers of bone metabolism. Interestingly, different types of forces will have specific consequences in bone remodeling, and their beneficial effects can be traced using different biomarkers. In this narrative review, we summarize the major mediators and events in bone remodeling, focusing on the effects of mechanical stimulation on bone metabolism, cell populations, and ultimately, bone health.

Regulatory Perspectives on Juvenile Animal Toxicologic Pathology

The Society of Toxicologic Pathology's Annual Virtual Symposium (2021) included a session on "Regulatory Perspectives on Juvenile Animal Toxicologic Pathology." The following narrative summarizes the key concepts from the four talks included in this symposium session chaired by Drs Deepa Rao and Alan Hoberman. These encompass an overview of various global regulations impacting the conduct of juvenile animal studies in pharmaceutical drug development and chemical toxicity assessments in a talk by Dr Alan Hoberman. Given the numerous regulatory guidances and legal statutes that have covered the conduct of juvenile animal studies and the recent harmonization of these guidances for pharmaceuticals, Dr Paul Brown provided an update on the harmonization of these guidances for pharmaceuticals, in the recently finalized version of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use S11 guidance document, "Nonclinical Safety Testing in Support of Development of Pediatric Medicines." The first two talks on regulations were followed by two talks focused on an evaluation of the postnatal development of two major organ systems relevant in juvenile animals. Dr Aurore Varela covered study design and endpoints impacting the skeletal system (bone), while Dr Brad Bolon presented a talk on the study design and conduct of neuropathology evaluations for the developing nervous system.

Biosafety of a novel covered self-expandable metal stent coated with poly(2-methoxyethyl acrylate) in vivo

Covered self-expandable metal stents (CSEMS) are often used for palliative endoscopic biliary drainage; however, the unobstructed period is limited because of sludge occlusion. The present study aimed to evaluate the biosafety of a novel poly(2-methoxyethyl acrylate)-coated CSEMS (PMEA-CSEMS) for sludge resistance and examine its biosafety in vivo. Using endoscopic retrograde cholangiopancreatography, we placed the PMEA-CSEMS into six normal porcine bile ducts and conventional CSEMS into three normal porcine bile ducts. We performed serological examination and undecalcified histological analysis at 1, 3, and 6 months during follow-up. In the bile ducts with PMEA-CSEMS or conventional CSEMS, we observed no increase in liver enzyme or inflammatory marker levels in the serological investigations and mild fibrosis but no inflammatory response in the histopathological analyses. Thus, we demonstrated the biosafety of PMEA-CSEMS in vivo.

Effects of Therapy with Fibrin Glue combined with Mesenchymal Stem Cells (MSCs) on Bone Regeneration: A Systematic Review

Cell therapy strategies using mesenchymal stem cells (MSCs) carried in fibrin glue have shown promising results in regenerative medicine. MSCs are crucial for tissue healing because they have angiogenic, anti-apoptotic and immunomodulatory properties, in addition to the ability to differentiate into several specialized cell lines. Fibrin sealant or fibrin glue is a natural polymer involved in the coagulation process. Fibrin glue provides a temporary structure that favors angiogenesis, extracellular matrix deposition and cell-matrix interactions. Additionally, fibrin glue maintains the local and paracrine functions of MSCs, providing tissue regeneration through less invasive clinical procedures. Thus, the objective of this systematic review was to assess the potential of fibrin glue combined with MSCs in bone or cartilage regeneration. The bibliographic search was performed in the PubMed/MEDLINE, LILACS and Embase databases, using the descriptors (“fibrin sealant” OR “fibrin glue”) AND “stem cells” AND “bone regeneration”, considering articles published until 2021. In this case, 12 preclinical and five clinical studies were selected to compose this review, according to the eligibility criteria. In preclinical studies, fibrin glue loaded with MSCs, alone or associated with bone substitute, significantly favored bone defects regeneration compared to scaffold without cells. Similarly, fibrin glue loaded with MSCs presented considerable potential to regenerate joint cartilage injuries and multiple bone fractures, with significant improvement in clinical parameters and absence of postoperative complications. Therefore, there is clear evidence in the literature that fibrin glue loaded with MSCs, alone or combined with bone substitute, is a promising strategy for treating lesions in bone or cartilaginous tissue.

Collagenated Porcine Heterologous Bone Grafts: Histomorphometric Evaluation of Bone Formation Using Different Physical Forms in a Rabbit Cancellous Bone Model

Collagenated porcine-derived bone graft materials exhibit osteoconductive properties and the development of different formulations intends to enhance bone regeneration. This study aims to evaluate bone healing in a rabbit cancellous bone defect in response to grafting with different physicochemical forms of heterologous porcine bone. Twenty-six adult male New Zealand White rabbits received two critical size femoral bone defects per animal (n = 52), each randomly assigned to one of the five tested materials (Apatos, Gen-Os, mp3, Putty, and Gel 40). Animals were sacrificed at 15- and 30-days post-surgery. Qualitative and quantitative (new bone, particle and connective tissue percentages) histological analyses were performed. Histomorphometry showed statistically significant differences in all evaluated parameters between mp3 and both Putty and Gel 40 groups, regardless of the timepoint (p < 0.05). Moreover, statistical differences were observed between Apatos and both Putty (p = 0.014) and Gel 40 (p = 0.007) groups, at 30 days, in regard to particle percentage. Within each group, regarding new bone formation, mp3 showed significant differences (p = 0.028) between 15 (40.93 ± 3.49%) and 30 (52.49 ± 11.04%) days. Additionally, intragroup analysis concerning the percentage of particles revealed a significant reduction in particle occupied area from 15 to 30 days in mp3 and Gen-Os groups (p = 0.009). All mp3, Gen-Os and Apatos exhibited promising results in terms of new bone formation, thus presenting suitable alternatives to be used in bone regeneration.

Simvastatin induces adverse effects on proliferation and mineralization of human primary osteoblasts

Background

Frequently statins were administered to reduce the LDL-concentration in circulating blood. Especially simvastatin (SV) is an often prescribed statin. Pleiotropic effects of these drugs were reported. Thus, the aim of this study was to evaluate effects of SV on osteoblastic mineralization.

Methods

After informed consent primary osteoblasts were collected from tissue surplus after treatment of 14 individuals in the Department of Cranio-Maxillofacial Surgery, University Hospital Münster. The cells were passaged according to established protocols. Viability, mineralization capability and osteoblastic marker (alkaline phosphatase) were determined at day 9, 13 and 16 after adding various SV concentrations (0.05 μM, 0.1 μM, 0.5 μM, 1.0 μM). Statistical analysis was performed using the Kruskal-Wallis-test.

Results

The cell cultures showed a time and dose-dependent significantly decreased viability (p < 0.01) and a significantly increased mineralization (p < 0.01) in a late mineralization stage after adding SV. The typical alteration of the alkaline phosphatase (ALP) levels during osteogenic differentiation was not recognizable.

Conclusions

The pleiotropic effects found for different SV concentrations were possibly originated from other mineralization pathways beside the ALP induced one. Additionally, possible alterations of protein expression levels during mineralization and investigation of possible deviating application of SV in other treatment fields can be considered after gaining a deeper insight in the affected mechanisms.

Clinical Performance of Short Expandable Dental Implants for Oral Rehabilitation in Highly Atrophic Alveolar Bone: 3-year Results of a Prospective Single-Center Cohort Study

Background and Objectives: Oral health-related quality of life (OHRQOL) is compromised during the post-implant healing period, especially when vertical augmentation is required. A long-term trial sought to evaluate a short dental implant system with an apically expandable macro-design. Materials and Methods: Over 4.5 years, patients with limited vertical alveolar bone were consecutively recruited into this prospective cohort study. Implant success rate, OHRQOL (Oral Health Impact Profile (OHIP)-14), implant stability, and crestal bone changes were evaluated. Results: Data from 30 patients (mean age: 64.6 years, range 44–83) were analyzed, which related to 104 implants (53 in the maxilla, 51 in the mandible). Over the mean follow-up (42.6 ± 16.4 months), the implant success rate was 94.7% in the mandible (two implants lost) and 83.6% in the maxilla (four implants lost; p = 0.096), and the prosthetic success rate was 100%. The median OHIP-14 scores improved from 23 (interquartile range (IQR) 9–25.5) to 2 (IQR 0–5; p < 0.001). The mean implant stability quotient (ISQ) was 71.2 ± 10.6 for primary stability and 73.7 ± 13.3 (p = 0.213) for secondary stability, without significant maxilla-versus-mandible differences (p ≥ 0.066). Compared to the baseline, median crestal bone changes after loading were 1.0 mm (IQR 0–1.3) and 1.0 mm (IQR 0.2–1.2) in the maxilla and mandible (p = 0.508), respectively, at the end of the first year, 1.1 mm (IQR 0–1.3) and 1.0 mm (IQR 0.1–1.2) (p = 0.382), respectively, at the end of the second year, and 1.2 mm (IQR 0–1.9) and 1.1 mm (IQR 0.1–1.2) (p = 0.304), respectively, at the end of the third year. Conclusions: In patients with limited vertical bone height, short implants with optimized macro-design constitute a reliable method for functional rehabilitation, avoiding extensive alveolar bone augmentation.

Structural and Metabolic Assessment of Bone

The assessment of bone structure and metabolism should focus on the bone strength. Many factors are involved, and although bone density is an important component, it is not the same as bone strength. Other aspects of bone quality include bone volume, micro-architecture, material composition, and ability to repair damage. This chapter briefly reviews some of the methods that can be used to assess both density and quality of bone. Non-invasive measurements of density or structure include dual X-ray absorptiometry (DXA), quantitative computed tomography, ultrasound, and magnetic resonance imaging. DXA is most widely used and has advantages of safety and accessibility, but there are limitations in the interpretation of the results, and in clinical practice positioning errors are frequently seen. Invasive methods are used primarily for research. Samples of bone can be used to measure structure by histology as well as micro-computed tomography and infra-red spectroscopy or backscattered electron microscopy. Force can be directly applied to bone samples to measure the bones strength. Impact microindentation is a new minimally invasive technique that measures bone hardness. Metabolic assessment includes blood and urine tests that reflect diseases that cause bone loss, particularly problems with mineral metabolism. Tetracycline-labelled bone biopsies are the standard for measuring bone formation. Non-invasive biochemical tests of bone formation and resorption can evaluate a patient's skeletal physiology.

[An optimized method for embedding undecalcified mouse tibias in plastic blocks]

OBJECTIVE

To optimize the method for embedding multiple undecalcified mouse tibias in plastic blocks, improve the efficiency and stability of plastic embedding and reduce the detachment rate of plastic slides.

METHODS

Thirty undecalcified tibias from 15 B6 mice were used for plastic embedding after calcein labeling, fixation, dehydration and infiltration. The tibias were embedded in cylindrical plastic blocks with a diameter of 4 mm. For each bone, the 1/4 proximal tibia was cut off, and the remaining 3/4 was used for re-embedding. Five bones were embedded in a single block with each bone standing closely on the surface of a flat plate. The samples were randomized into control and experimental groups in all the processes of embedding, sectioning and staining. In the 3 groups with modified embedment, flowing CO2 was added into the embedding solution, embedding solution was applied to the section surface, and the slides were heated at 95 ℃ for 15 min. The polymerization time, slide detachment rate, bone formation and osteoblast parameters were analyzed.

RESULTS

We prepared 6 plastic blocks, each containing 5 tibias, whose cross sections were on the same plane. The blocks were completely polymerized and suitable for sectioning. Flowing CO2 into the embedding solution reduced the polymerization time and increased the rate of complete polymerization. Application of the embedding solution on the section surface significantly reduced the detachment rate of the sections (P < 0.05) without affecting bone formation analysis (P > 0.05). Heating the slides significantly lowered the detachment rate of the sections (P < 0.05) without affecting osteoblast analysis (P > 0.05).

CONCLUSIONS

The optimized method allows effective embedding of multiple undecalcified mice tibias in the same block and can be an ideal method for histological analysis of undecalcified bones.

A 12-month prospective exploratory study of muscle and fat characteristics in individuals with mild-to-moderate hip osteoarthritis

Background

Reductions in lower extremity muscle strength, size and quality and increased fat content have been reported in advanced hip osteoarthritis (OA). Whether these differences are also evident at earlier stages of the disease and the extent to which they might develop over time is unclear. The main purpose of this 12-month exploratory prospective study was to compare changes in muscle and fat characteristics in individuals with mild-to-moderate hip OA and healthy controls.

Methods

Fourteen individuals with mild-to-moderate symptomatic and radiographic hip OA (n = 9 unilateral; n = 5 bilateral), and 15 healthy controls similar in age and sex without symptoms or radiographic hip OA were assessed at baseline and at 12-month follow-up. Maximal voluntary isometric strength of the hip and knee muscle groups was assessed using an isokinetic dynamometer. Lower extremity lean and fat mass were assessed using dual-energy x-ray absorptiometry, and thigh muscle and fat areas and thigh muscle density were assessed using peripheral quantitative computed tomography.

Results

Knee extension (p = 0.01), hip extension (p < 0.01), hip flexion (p = 0.03), and hip abduction (p < 0.01) strength, lower extremity lean mass (p < 0.01), thigh muscle area (p = 0.03), and thigh muscle density (p < 0.01) were significantly lower in hip OA compared to controls. Hip extension (p < 0.05), hip flexion (p = 0.03), and hip abduction (p = 0.03) strength significantly declined over the follow-up period in the hip OA group.

Conclusions

Pre-existing deficits in hip muscle strength in individuals with mild-to-moderate hip OA were accentuated over 12-months, though no changes in symptoms or joint structure were observed. A longer follow-up period is required to establish whether strength deficits drive clinical and structural decline in these patients. Interventions to prevent or slow declines in strength may be relevant in the management of mild-to-moderate hip OA.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2668-z) contains supplementary material, which is available to authorized users.